Is there an Ejection Port Diagram for the 450 Bushmaster?

[macmac]

Here's the diagram as measured on my rifle.

The 15 degree slant I refer to is the tilt that the bur / mill / stone, whatever, is tilted toward the top of the receiver while grinding. In other words, don't position the cutting tool perpendicular to the opening. As WC said, many folks who build uppers for this and other thumper calibers just use a Dremel with a carbide bur or rotary stone and I've seen some of their work. It looks fine. Obviously, don't balance the upper in your lap on a stool and do it. Affix it firmly to a work surface and set up a rest for your hand holding the dremel. Make many light cuts and it doesn't have to be aerospace precision. Just don't cut into the cover detent area.



Good Luck

Hoot

EDIT

Oops! In my haste to get the image made and annotated, while the wife was tapping her toe, waiting to go get groceries, I printed it upside down. The top rail is on the bottom in the picture. It doesn't effect what needs to be done. Also, in case you don't realize it, the widening is accomplished by only removing material from the top half of the port where the small step lip is located.

Hoot

This helps a lot..will see about using this with the one my son and I are getting ready to build!

[macmac]

I took off on upper and lower area.

[Hoot]

So, you took it off of the bottom of the port as opposed to Bushmaster taking it off the top. I guess it doesn't matter which side gives way as long as one of them does. On an aside, I believe the 458S and 50B have a fatter case (~.545) versus the 450B (~.500). I'm guessing as I only have a .50AE spent case I found at the range to measure.

Thanks,

Hoot

[macmac]

I hope these show up.. I hate trying to up load.. lol

[macmac]

So, you took it off of the bottom of the port as opposed to Bushmaster taking it off the top. I guess it doesn't matter which side gives way as long as one of them does. On an aside, I believe the 458S and 50B have a fatter case (~.545) versus the 450B (~.500). I'm guessing as I only have a .50AE spent case I found at the range to measure.

Thanks,

Hoot

I actually took some off top and bottom...wanted to maintain dust cover function..I also didnt cut it on angle..

[Blasternank]

Here's the diagram as measured on my rifle.

The 15 degree slant I refer to is the tilt that the bur / mill / stone, whatever, is tilted toward the top of the receiver while grinding. In other words, don't position the cutting tool perpendicular to the opening. As WC said, many folks who build uppers for this and other thumper calibers just use a Dremel with a carbide bur or rotary stone and I've seen some of their work. It looks fine. Obviously, don't balance the upper in your lap on a stool and do it. Affix it firmly to a work surface and set up a rest for your hand holding the dremel. Make many light cuts and it doesn't have to be aerospace precision. Just don't cut into the cover detent area.



Good Luck

Hoot

EDIT

Oops! In my haste to get the image made and annotated, while the wife was tapping her toe, waiting to go get groceries, I printed it upside down. The top rail is on the bottom in the picture. It doesn't effect what needs to be done. Also, in case you don't realize it, the widening is accomplished by only removing material from the top half of the port where the small step lip is located.

Hoot

So Hoot or anyone that can answer this: Do you basically only have to take material off of the top rear section of the ejection port? From the upper left section to the detent spot? i want to try this but I'm not too good with tools like this and am afraid I'll screw it up.

Thanks.

[Hoot]

So Hoot or anyone that can answer this: Do you basically only have to take material off of the top rear section of the ejection port? From the upper left section to the detent spot? i want to try this but I'm not too good with tools like this and am afraid I'll screw it up.

Thanks.

I swear, that upside down picture is going to haunt me the rest of my life.

No. Holding the upper upright and with the ejection port facing you, the cover detent spot represents the left-most starting point you grind off the top part going right, toward the chamber.

Pull the bolt back with a spent case in it and observe the first point where that case flips outward as it ejects. That is the area you remove. Since the spent case is ejected slightly upward, you remove the upper portion of the port.

As long as you're not in a rush and work carefully, you will do just fine. The process is very forgiving and the material isn't hard like gun steel. I've seen it done with a rat-tail file. I've seen it done with a dremel and stone, a dremel and rotary sanding cylinder and IMHO, the best way, a dremel with a carbide burr. I've seen it done with a mill, if you have access to one. If it's a used upper, degrease it so the chips don't stick to everything.

BTW, what lead time were you quoted on your barrel and bolt?

Hoot

[Blasternank]

Thanks Hoot! You may need to edit that picture so people don't continually harass you! With regards to wait times: Ballistic Advantage quoted 12 weeks, but Trident Armory, in the Market section, said he will begin making barrels this week. So within a few weeks you can have it in hand. That's what they told me over the phone.

Thanks.

[wildcatter]

Ok, I stand Corrected. The first one I saw, couldn't get the dust cover to work, but apparently they have figured it out..

..t

[3rdgeargrndrr]

Virgin upper width







450 Bushmaster upper width